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1 | package threads::shared; |
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2 | |
3 | use 5.007_003; |
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4 | use strict; |
5 | use warnings; |
6 | use Config; |
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7 | |
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8 | BEGIN { |
9 | unless ($Config{useithreads}) { |
10 | my @caller = caller(2); |
11 | die <<EOF; |
12 | $caller[1] line $caller[2]: |
13 | |
14 | This Perl hasn't been configured and built properly for the threads |
15 | module to work. (The 'useithreads' configuration option hasn't been used.) |
16 | |
17 | Having threads support requires all of Perl and all of the modules in |
18 | the Perl installation to be rebuilt, it is not just a question of adding |
19 | the threads module. (In other words, threaded and non-threaded Perls |
20 | are binary incompatible.) |
21 | |
22 | If you want to the use the threads module, please contact the people |
23 | who built your Perl. |
24 | |
25 | Cannot continue, aborting. |
26 | EOF |
27 | } |
28 | } |
29 | |
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30 | require Exporter; |
31 | our @ISA = qw(Exporter); |
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32 | our @EXPORT = qw(share cond_wait cond_broadcast cond_signal _refcnt _id _thrcnt); |
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33 | our $VERSION = '0.90'; |
34 | |
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35 | if ($Config{'useithreads'}) { |
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36 | *cond_wait = \&cond_wait_enabled; |
37 | *cond_signal = \&cond_signal_enabled; |
38 | *cond_broadcast = \&cond_broadcast_enabled; |
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39 | require XSLoader; |
40 | XSLoader::load('threads::shared',$VERSION); |
41 | } |
42 | else { |
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43 | *share = \&share_disabled; |
44 | *cond_wait = \&cond_wait_disabled; |
45 | *cond_signal = \&cond_signal_disabled; |
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46 | *cond_broadcast = \&cond_broadcast_disabled; |
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47 | } |
48 | |
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49 | |
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50 | sub cond_wait_disabled { return @_ }; |
51 | sub cond_signal_disabled { return @_}; |
52 | sub cond_broadcast_disabled { return @_}; |
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53 | sub share_disabled { return @_} |
54 | |
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55 | $threads::shared::threads_shared = 1; |
56 | |
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57 | |
58 | sub threads::shared::tie::SPLICE |
59 | { |
60 | die "Splice not implemented for shared arrays"; |
61 | } |
62 | |
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63 | __END__ |
64 | |
65 | =head1 NAME |
66 | |
67 | threads::shared - Perl extension for sharing data structures between threads |
68 | |
69 | =head1 SYNOPSIS |
70 | |
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71 | use threads; |
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72 | use threads::shared; |
73 | |
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74 | my $var : shared; |
75 | |
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76 | my($scalar, @array, %hash); |
77 | share($scalar); |
78 | share(@array); |
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79 | share(%hash); |
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80 | my $bar = share([]); |
81 | $hash{bar} = share({}); |
82 | |
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83 | { lock(%hash); ... } |
84 | |
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85 | cond_wait($scalar); |
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86 | cond_broadcast(@array); |
87 | cond_signal(%hash); |
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88 | |
89 | =head1 DESCRIPTION |
90 | |
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91 | By default, variables are private to each thread, and each newly created |
92 | thread gets a private copy of each existing variable. This module allows |
93 | you to share variables across different threads (and pseudoforks on |
94 | win32). It is used together with the threads module. |
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95 | |
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96 | =head1 EXPORT |
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97 | |
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98 | C<share>, C<lock>, C<cond_wait>, C<cond_signal>, C<cond_broadcast> |
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99 | |
100 | =head1 FUNCTIONS |
101 | |
102 | =over 4 |
103 | |
104 | =item share VARIABLE |
105 | |
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106 | C<share> takes a value and marks it as shared. You can share a scalar, array, |
107 | hash, scalar ref, array ref or hash ref. C<share> will return the shared value. |
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108 | |
109 | C<share> will traverse up references exactly I<one> level. |
110 | C<share(\$a)> is equivalent to C<share($a)>, while C<share(\\$a)> is not. |
111 | |
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112 | A variable can also be marked as shared at compile time by using the |
113 | C<shared> attribute: C<my $var : shared>. |
114 | |
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115 | =item lock VARIABLE |
116 | |
117 | C<lock> places a lock on a variable until the lock goes out of scope. If |
118 | the variable is locked by another thread, the C<lock> call will block until |
119 | it's available. C<lock> is recursive, so multiple calls to C<lock> are |
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120 | safe -- the variable will remain locked until the outermost lock on the |
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121 | variable goes out of scope. |
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122 | |
123 | If a container object, such as a hash or array, is locked, all the elements |
124 | of that container are not locked. For example, if a thread does a C<lock |
125 | @a>, any other thread doing a C<lock($a[12])> won't block. |
126 | |
127 | C<lock> will traverse up references exactly I<one> level. |
128 | C<lock(\$a)> is equivalent to C<lock($a)>, while C<lock(\\$a)> is not. |
129 | |
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130 | Note that you cannot explicitly unlock a variable; you can only wait for |
131 | the lock to go out of scope. If you need more fine-grained control, see |
132 | L<threads::shared::semaphore>. |
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133 | |
134 | =item cond_wait VARIABLE |
135 | |
136 | The C<cond_wait> function takes a B<locked> variable as a parameter, |
137 | unlocks the variable, and blocks until another thread does a C<cond_signal> |
138 | or C<cond_broadcast> for that same locked variable. The variable that |
139 | C<cond_wait> blocked on is relocked after the C<cond_wait> is satisfied. |
140 | If there are multiple threads C<cond_wait>ing on the same variable, all but |
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141 | one will reblock waiting to reacquire the lock on the variable. (So if |
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142 | you're only using C<cond_wait> for synchronisation, give up the lock as |
143 | soon as possible). The two actions of unlocking the variable and entering |
144 | the blocked wait state are atomic, The two actions of exiting from the |
145 | blocked wait state and relocking the variable are not. |
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146 | |
147 | It is important to note that the variable can be notified even if no |
148 | thread C<cond_signal> or C<cond_broadcast> on the variable. It is therefore |
149 | important to check the value of the variable and go back to waiting if the |
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150 | requirement is not fulfilled. |
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151 | |
152 | =item cond_signal VARIABLE |
153 | |
154 | The C<cond_signal> function takes a B<locked> variable as a parameter and |
155 | unblocks one thread that's C<cond_wait>ing on that variable. If more than |
156 | one thread is blocked in a C<cond_wait> on that variable, only one (and |
157 | which one is indeterminate) will be unblocked. |
158 | |
159 | If there are no threads blocked in a C<cond_wait> on the variable, the |
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160 | signal is discarded. By always locking before signaling, you can (with |
161 | care), avoid signaling before another thread has entered cond_wait(). |
162 | |
163 | C<cond_signal> will normally generate a warning if you attempt to use it |
164 | on an unlocked variable. On the rare occasions where doing this may be |
165 | sensible, you can skip the warning with |
166 | |
167 | { no warnings 'threads'; cond_signal($foo) } |
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168 | |
169 | =item cond_broadcast VARIABLE |
170 | |
171 | The C<cond_broadcast> function works similarly to C<cond_signal>. |
172 | C<cond_broadcast>, though, will unblock B<all> the threads that are blocked |
173 | in a C<cond_wait> on the locked variable, rather than only one. |
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174 | |
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175 | =back |
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176 | |
177 | =head1 NOTES |
178 | |
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179 | threads::shared is designed to disable itself silently if threads are |
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180 | not available. If you want access to threads, you must C<use threads> |
181 | before you C<use threads::shared>. threads will emit a warning if you |
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182 | use it after threads::shared. |
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183 | |
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184 | =head1 BUGS |
185 | |
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186 | C<bless> is not supported on shared references. In the current version, |
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187 | C<bless> will only bless the thread local reference and the blessing |
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188 | will not propagate to the other threads. This is expected to be |
189 | implemented in a future version of Perl. |
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190 | |
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191 | Does not support splice on arrays! |
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192 | |
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193 | Taking references to the elements of shared arrays and hashes does not |
194 | autovivify the elements, and neither does slicing a shared array/hash |
195 | over non-existent indices/keys autovivify the elements. |
196 | |
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197 | =head1 AUTHOR |
198 | |
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199 | Arthur Bergman E<lt>arthur at contiller.seE<gt> |
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200 | |
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201 | threads::shared is released under the same license as Perl |
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202 | |
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203 | Documentation borrowed from Thread.pm |
204 | |
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205 | =head1 SEE ALSO |
206 | |
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207 | L<threads>, L<perlthrtut> |
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208 | |
209 | =cut |